Allometric relationships between above-ground biomass increment and stand characteristics for crimean pine in Taşköprü, Turkey

Background: Biomass increment, one of the main components of net primary production (NPP) in forest ecosystems, plays an important role as well as total biomass in the global carbon cycle. In this study, the changes of increments of the above-ground total, stem and branch biomasses depending on stand characteristics (i.e., stand age, stand density, and site index) were investigated, and these relations were modeled for Crimean pine ( Pinus nigra J.F.Arnold subsp. pallasiana (Lamb.) Holmboe) stands in Taşköprü region of Türkiye. Data were obtained from 109 sample trees within 74 sample plots representing the wide range of possible stand characteristics. Results: The equations developed for above-ground total, stem and branch biomass increments have quite high coefficients of determination ( R 2 =0.784, 0.684 and 0.780, respectively), whereas low root mean square errors ( RMSE =0.749, 0.692 and 0.116, respectively). The results indicated that the biomass increment estimates from the allometric equations developed were decreasing with stand age and increasing with stand density and site index and also stand density is the strongest stand characteristic on biomass increment. Conclusion: The estimates are also consistent with the growth patterns, so the equations can be used for biomass increment estimations and also for carbon storage and NPP projections for Crimean pine stands of the region.